In "capture new state", there is this step:

If namedElements[transitionName] does not exist, then set namedElements[transitionName] to a new captured element struct.

However, it doesn't mention where to insert the element, which means by default we would be adding it at the end of the ordered map. It is the more convenient default to implement, but is this correct? You might expect to want to preserve the paint order or such (slightly more of a pain to do, but possible)

cc @noamr @khushalsagar @fantasai @tabatkins @vmpstr